DE 10 2004 052 972 A1 discloses a wound flat material used in calibrating extruded plastics pipes. The flat material overlaps in portions and is in close mutual contact in the overlap region. DE 10 2007 026 309 discloses a similar device, also in the case of which portions are in close superposition. The larger the overlap surfaces and the larger the contact surfaces of the flat material to the plastics pipe, the greater the friction which occurs.